Contemporary hard disk drives include an actuator assembly pivoting through an actuator pivot to position one or more read-write heads, embedded in sliders, each over a rotating disk surface. The data stored on the rotating disk surface is typically arranged in concentric tracks. To access the data of a track, a servo controller first positions the read-write head by electrically stimulating the voice coil motor, which couples through the voice coil and an actuator arm to move a head gimbal assembly in lateral positioning the slider close to the track. Once the read-write head is close to the track, the servo controller typically enters an operational mode known herein as track following. It is during track following mode that the read-write head is used to access data stored in the track. Micro-actuators provide a second actuation stage for lateral positioning the read-write head during track following mode. They often use an electrostatic effect and/or a piezoelectric effect to rapidly make fine position changes. They have doubled the bandwidth of servo controllers and are believed essential for high capacity hard disk drives from hereon.
A central feature of the hard disk drive industry is its quest for greater data storage density, leading to continued reduction in track width, and the size of the read head within the read-write head. As the read head shrinks, the read signal it can generate will grow weaker. While contemporary hard disk drives have a preamplifier located in the actuator assembly, this weak read signal must travel from the slider a path with significant resistance before it can be amplified. What is needed is a mechanism strengthening the read signal before it leaves the slider.